The present invention relates to a method for the preparation of alkyl polyglycosides by the reaction of a saccharide and an alcohol, and in particular to a method for treating water emulsion drawn off from the alkyl polyglycoside reaction.
Alkyl glycosides are conveniently prepared by reacting an alcohol of the type and chain length which is desired to form the "alkyl" portion of the glycoside of interest with a saccharide reactant (e.g., a monosaccharide such as glycose, xylose, arabinose, galactose, fructose, etc., or a polysaccharide such as starch, hemicellulose, lactose, maltose, melibiose, etc.) or with a glycoside starting material wherein the aglycone portion thereof is different from the alkyl substituent desired for the ultimate alkyl glycoside product of interest. Typically, such reaction is conducted at an elevated temperature and in the presence of an acid catalyst.
Water is formed as a by-product of the reaction between a fatty alcohol and a saccharide. The water is only sparingly soluble in the fatty alcohol, and undissolved water can result in the formation of unwanted by-products. Consequently, the water is removed as it is formed, usually as part of an emulsion containing fatty alcohol, dextrose, alkyl polyglycosides and organic acids, and is typically collected in a separator. It is desirable to break down this emulsion so that the fatty alcohol can be recovered and recycled. The water, with reduced organic loading, can be disposed of. However, the emulsion cannot easily be broken simply by the use of high temperature (e.g. 150.degree. F.-175.degree. F.) and/or longer residence times. What is needed is a method for breaking down the emulsion quickly and efficiently to facilitate separation of its components.